Peterborough United manager Graham Westley had urged his players to take inspiration from the Oscar-nominated film, The Revenant, and then watched their remarkable survival instinct on Saturday as they produced the performance of the FA Cup fourth round.

The third tier side twice looked down and out but battled back in the dying minutes to earn a 2-2 draw at Premier League West Bromwich Albion.

On a day when the big guns largely extinguished the hopes of the dreaming underdogs to make progress into the fifth round, the League One team proved indomitable after Saido Berahino, given a rare start, had twice put Albion ahead at the Hawthorns.

Peterborough's heroes were Shaquile Coulthirst, who equalised Berahino's first half goal in the 79th minute, and Jon Taylor, who then answered what had looked to be a late winner from the Albion striker with just four minutes left to earn his side a lucrative replay at their London Road home.

"The lads showed some great composure, great maturity and desire," said Westley, who had criticised their last league performance and suggested they learn about the human spirit from The Revenant, the saga of a man's fight for survival after being attacked by a bear. Apparently, it worked.

Portsmouth, who plunged into the fourth tier of the English game after financial woes, sniffed a sensation at a frantic Fratton Park before Premier League Bournemouth battled from behind to win 2-1.

The 2008 winners, now a supporter-owned club, had rekindled memories of the days when they used to be Bournemouth's south coast masters as they went ahead through their 31-year-old journeyman winger, Gary Roberts, just before half-time.

But Bournemouth belatedly flexed their muscles, substitute Josh King earning a 71st minute equaliser before Marc Pugh ruined the party with an 83rd minute winner.

Arsenal maintained their push towards winning the Cup for a third successive year as Alexis Sanchez, back in the starting line-up for the first time since November after injury, scored the winner in a 2-1 victory over Championship side Burnley in North London.

The second tier side had provided some resistance after England defender Calum Chambers had put the Gunners ahead with Sam Vokes powering home a headed equaliser.

After the break, though, the class of Sanchez told as he swept home a cross to ensure the Gunners are still on course to emulate the back-to-back trebles of Blackburn Rovers and Wanderers back in the Victorian era.

Arsenal manager Arsene Wenger, protecting his record of only losing to a lower-league team once in 41 FA Cup ties, was happy to overcome what he felt was tough opposition.

"Burnley are a good side. When they equalised suddenly you could see, energy, commitment, and we had to dig deep to win the game," he told the BBC.

Favourites through to fifth round

Some of the other favourites also booked their fifth round ties with some comfort.

Manchester City piled further misery on struggling Aston Villa with a 4-0 win, adorned by a hat-trick from teenage prospect Kelechi Iheanacho.

Villa's hopes of some blessed relief from their Premier League woes were swiftly extinguished when the 19-year-old Nigerian put City ahead after just four minutes at Villa Park.

Iheanacho then doubled City's lead, converting from the penalty spot. He completed his treble after latching on Micah Richards' poor back pass before Raheem Sterling completed the rout with City's fourth.

"Kelechi is a very good young player," City manager Manuel Pellegrini told the BBC.

"We let (Stevan) Jovetic and (Edin) Dzeko go because I see Kelechi every day and know what he can do."

In two other all-Premier League clashes, Crystal Palace beat Stoke City 1-0 with a splendid individual effort from Wilfried Zaha but Liverpool, despite making wholesale changes after reaching the League Cup final in midweek, were stalled in their second Wembley quest with a goalless draw against West Ham United.

Spurs took no chances, fielding a strong side as they accounted for League One Colchester United 4-1, featuring a double from Belgian Nacer Chadli.